P-17
Rapid detection system of beer-spoilage bacteria by FISH. Several species of Lactobacillus, as well as Pectinatus, are
known to grow in beer and cause beer spoilage. For this reason, microbiological
quality assurance in breweries focuses on the detection of these microorganisms.
The microbiological quality of beer has been traditionally assessed on the basis
of selective culture detection. Upon the detection of microorganisms,
morphological examinations, antibody techniques and/or PCR methods are performed
to identify the microorganisms. Since this technique requires at least several
days for cultivation, a more rapid and accurate detection method for
beer-spoilage bacteria has been desired. For the past decade, FISH (fluorescence
in situ hybridization) method has made rapid progress and gained wide
acceptance in the environmental and clinical field as a tool for the enumeration
and identification of the target bacteria. Last year at the ASBC annual meeting,
we presented the direct detection method for Pectinatus on a filter
membrane using DNA probes targeted to the rRNA molecules. In this approach, we
showed this method had higher sensitivity to detect Pectinatus compared
with the conventional culturing method. In this study, we applied the FISH
method to the detection of Lactobacillus species. The cell walls of
Lactobacillus species are generally known to be more rigid and thicker
than those of Pectinatus species, and therefore we had to take some
measures in order for the probes to penetrate the cell walls. To achieve this,
we designed the probes specific to the target Lactobacillus and adopted
PNA (Peptide Nucleic Acid) as probes for the detection. Finally, we established
the experimental condition for the FISH in this application and confirmed that
beer-spoilage Lactobacillus species could be detected rapidly without a
culturing step.
Takaomi Yasuhara is a specialist on molucular biology at the Brewing
Research & Development Laboratory, Asahi Breweries. He received his M.S. degree
in bio-engineering from Osaka University, where he majored in yeast genetics
directed by Prof. Ohshima, and joined Asahi Breweries, Ltd. in 1991. During
1991-1998, he was engaged in fundamental research in Oncology and Allergology.
Since 1999, he has been researching microbiological quality assurance in
brewing.
TAKAOMI YASUHARA, Yasuo Motoyama, Kazunori Shibata, and Katsuyuki Kawatsura.
Brewing Research Development Laboratory, Asahi Breweries Ltd., Moriya, Ibaraki,
Japan.